This invention relates to a part program creation method through which a part program necessary for the creation of an NC tape can be simply created. More particularly, the invention relates to a method of creating a complete part program merely by storing the non-variable portions of a part program in a memory beforehand and then entering the variable portions of the part program.
An NC machine tool is operated as specified by machining program data (NC data) stored on an NC tape to subject a workpiece to prescribed machining. To create an NC tape for a certain cutting operation, numerical control information and other machining conditions are punched into a paper tape in accordance with predetermined rules. The numerical control information includes all the information necessary for machining, such as numerical values obtained from a design drawing and relating to the dimensions of the workpiece that is to be machined, feed velocity, and the like. When machining the workpiece by means of an NC machine tool, the NC tape is loaded into the tape reader of an NC device so that the various instructions recorded on the NC tape may be read successively, the NC device responds by executing the instructions to perform the prescribed machining. Thus, an NC tape is a record of NC data, and comprises, for example, a paper tape, magnetic tape or bubble cassette memory. Since considerable time and experience is required to create the NC tape, an apparatus for creating an NC tape automatically has recently been developed and put into practical use. This NC tape automatic creation apparatus includes a graphic display, keyboard, printer and the like and is extremely useful in preparing NC tapes in a simple, accurate and rapid manner. This NC tape automatic creation apparatus includes a microprocessor and an internal main memory for storing the NC tape creation software (system program).
To create an NC tape by such an NC tape automatic creation apparatus, the prescribed system program is loaded into the main memory, and a group of data (part program) specifying motion of a tool along a contour must be created and entered in accordance with predetermined rules. The part program ordinarily comprises a graphic definition state for defining a graphic, a motion definition statement (motion statement) specifying tool path, and auxiliary machining information such as feed velocity and spindle rotating velocity, and a programmer must create the part program at his desk from a design drawing. Therefore, such creation of a part program is disadvantageous in that it is both a troublesome and time-consuming task and can only be accomplished by a programmer having considerable programming skill.